1. Field of the Invention
This invention pertains to pipe handling equipment, and more particularly to apparatus for transferring pipes to and from an oil drilling rig.
2. Description of the Prior Art
Various equipment has been developed to transfer materials and articles between locations having different vertical and horizontal positions. For example, U.S. Pat. No. 3,103,291 shows a vehicle useful for loading and unloading airplanes, and U.S. Pat. No. 3,446,379 shows a scissors-type high lift elevating mechanism. U.S. Pat. No. 4,162,873 discloses an extensible boom lift which includes a table mounted on a scissors-type lifting device and supporting a beam which is rotatable about a vertical axis. An extensible boom is supported by the rotatable beam.
The handling of long and heavy pipes as used in oil drilling operations presents difficult problems. Such pipes are heavy, cumbersome, and dangerous to move from a stack thereof to a drilling rig and back to the stack. Specifically, accurately positioning a pipe where it can be readily grabbed by a pipe elevator for adding to a string of pipes is a formidable task.
An example of oil pipe handling equipment is shown in U.S. Pat. No. 2,617,547, which discloses a pipe loading device having lifting arms attached to a chassis and adapted to raise lengths of pipe from the ground to a pair of transversely inclined pipe rests. The pipe rests are supported by a scissors-type lifting platform for vertically raising the pipes to a higher level. The device of U.S. Pat. No. 2,617,547 is disadvantageous because the pipe on the platform cannot be transferred under power along a longitudinal axis, and also because the pipe remains horizontal during lifting operations, thereby making it difficult to grab by a pipe elevator. U.S. Pat. No. 2,676,715 shows a self-loading truck having loading arms for raising pipe from the ground to a selected height above the bed of the truck. The truck does not include means for unloading the pipe from a drilling rig.
U.S. Pat. No. 3,785,506 shows a drill pipe handling apparatus for controlling the descent of a pipe from a derrick floor to a lower pipe support, and from the pipe support to a pipe rack therebelow. The device of U.S. Pat. No. 3,785,506 is not capable of raising pipe from the ground to a derrick floor. U.S. Pat. No. 3,810,553 illustrates a pipe handling device which is capable of lifting a pipe from the ground onto a pair of connected dollies. The dollies are reciprocable to move the pipe longitudinally onto and up an inclined chute to the rig platform. The device is also capable of the reverse operation of transporting a pipe from the rig to the ground. U.S. Pat. No. 4,054,210 shows a pipe carrier which is movably mounted on an elevated first cable suspended between the ground and derrick. A disadvantage of the devices of U.S. Pat. Nos. 3,785,506; 3,810,553; and 4,054,210 is that they cannot be readily moved to other stacks of pipes or derricks.
U.S. Pat. No. 4,236,861 shows a pipe handler with a scissors lift for supporting a platform and pipe support racks. A pivotable lifting mechanism transports the pipes from the ground to the platform rails. A selected pipe is positioned over a pipe lifting device which raises it vertically above the rails to a desired height. The handler does not include any mechanism for assisting the horizontal transfer of a pipe to another structure.
Thus, a need exists for a transportable pipe handling device which is capable of efficiently manipulating heavy pipe through large vertical and horizontal distances between a stack thereof and a rig platform.